For levelling a horizontal plane in engineering construction, a level may be provided for calibrating such a horizontal level. For checking the verticality of a building site, a plumb may be provided for this purpose. It will be costly and inconvenient to purchase and prepare the horizontal level and the vertical plumb separately.
In the circumstances where the levelling and verticality as well as angle calibration must be done simultaneously, such as found in an interior uphostery engineering, to prepare and use the conventional level and plumb separately may defer the engineering work and decrease the job efficiency.
Therefore, the present inventor has invented the device having laser level and angle calibrator combinable on an integrated instrument.